Full Walls Research Articles

Experimental performance of FRCM retrofit on out-of-plane behaviour of clay brick walls

Abstract In this paper the capacity of an innovative composite basalt grid with inorganic matrix (FRCM) has been evaluated both in terms of repairing pre-damaged and strengthening clay brick walls under out-of-plane loads. Experimental tests have been performed on full scale clay brick walls subjected to out-of-plane loads. A wall, damaged after a test, has been repaired by means of basalt FRCM. A similar wall has been tested directly, without pre-damage, after strengthening by means of FRCM. This allowed to remark the effect of retrofitting pre-damaged and new walls. To simulate a non-uniform out-of-plane behaviour of the wall, two adjacent edges of the wall have been constrained and the other two were left free while a pointwise normal force has been applied at the free opposite corner of the wall. The purpose of this work was to assess the potentiality of FRCM to recover the capacity of a wall after significant damage and to increase the global response of strengthened wall not previously damaged. The experimental results demonstrated that the externally bonded strengthening was able to prevent a brittle failure and it was not affected by debonding; ultimate load of the retrofitted wall almost doubled with respect to the unreinforced configuration, despite complex stress state, and that the failure was governed by shear sliding at higher displacement levels.

Effects of vertical stresses and flanges on seismic behavior of unreinforced brick masonry

Lateral in-plane response plays crucial role in seismic behavior of masonry structures. The aim of this article is to experimentally investigate the effects of vertical stresses and flanges (transverse walls) on the lateral in-plane response of the unreinforced brick masonry (URBM) walls. The experimental work included lateral in-plane quasi-static cyclic tests on full-scale walls (both with & without flanges). The vertical stresses resulting from typical single and two story unreinforced masonry buildings were simulated on full scale URBM walls. Flanges were introduced at both ends of the in-plane wall in single direction. In essence, the lateral in-plane stiffness & strength, deformability and energy dissipation of the two classes of walls are compared and the differences are quantified to help understand the effects of flanges on the in-plane response of masonry walls. The resulting damage mechanism and failure modes for each case are critically analyzed. The experimental results indicate that both vertical stresses and flanges incorporation significantly improved seismic response of URBM walls. In addition, the participation of flanges is critical in both vertical stress conditions.

Seismic response of CFS shear walls sheathed with nailed gypsum panels: Experimental tests

Among the several available building systems, constructions involving cold-formed steel (CFS) profiles represent an efficient and reliable solution. These systems are very suitable to be used in pre-fabricated modular constructions, thanks to their lightness and possibility to automate the building process. In a framework of the European project ELISSA (Energy Efficient LIghtweight-Sustainable-SAfe-Steel Construction), which was devoted to the development and demonstration of CFS modular systems, an experimental campaign aimed at investigating the seismic response of this system was carried out at University of Naples Federico II. Specifically, the studied system was a sheathing-braced CFS solution, in which the seismic resistant elements were made of CFS stud shear walls laterally braced with gypsum-based panels. The sheathing panels were attached to the CFS frame by means of ballistic nails, whereas clinching points were used for steel-to-steel connections. This paper shows the results of tests performed on shear walls and on the relevant ballistically nailed panel-to-steel connections. In particular, four full scale shear walls were tested, in which the influence of the aspect ratio, the type of loading and the effect of finishing was investigated.

In-Plane Behavior of Plain and Strengthened Solid Brick Masonry Walls

Unreinforced masonry structures are generally vulnerable to earthquake actions. Brittle masonry walls are very stiff and attract considerable seismic forces which cannot be sustained without cracking. In order to enhance ductility and load bearing capacity, certain strengthening techniques need to be applied. An experimental program concerning in-plane behavior of solid clay brick masonry walls was performed at the Institute for Materials and Structures, Faculty of Civil Engineering University of Sarajevo, in cooperation with Institute for Lightweight Structures and Conceptual Design, University of Stuttgart. The physical models include two unconfined unreinforced full scale masonry walls L/H/D=233/237/25cm and two strengthened full scale walls jacketed on both sides with 5cm thick concrete and reinforced with Q196 steel mesh. Twelve reduced scale walls L/H/D = 100/100/25cm were additionally constructed in order to test different strengthening methods which include one-or two-sided jacketing and CFK 150 strips. Specimens were exposed to cyclic shear as well as to monotonic push over loading program for different vertical stress levels with the aim to quantify shear strength, stiffness and energy dissipation. For lower vertical loads the tested walls exhibit rigid body rotation in each displacement cycle. For higher precompression mixed flexural and shear failure mode was registered, characterized by toe crushing and diagonal cracking. No separation of jacketing from the masonry was detected. Numerical models of tested wall panels were developed using finite element programs.

Simple Numerical Homogenization Model for FRCM Reinforced Masonry Panels Subjected to Out-of-Plane Loads

The paper deals with the analysis of FRCM reinforced masonry panels in simple bending by means of a two-step homogenization approach. In the first step, homogenization is performed on unreinforced masonry through a straightforward procedure already validated for in-plane loaded FRCM reinforced panels, where the elementary cell is discretized by means of 24 CST elastic elements (bricks) and joints are reduced to interfaces with holonomic softening behavior. Out-of-plane homogenized quantities (moment-curvature relationships) are then obtained by simple on-thickness integration. At a structural level (step two), masonry is modeled with rigid elements and homogenized torsional and bending springs, whereas FRCM by two noded trusses with equivalent mechanical properties evaluated on the base of experimental data available. The implementation is handled within the commercial FE software Abaqus. As a matter of fact, the Concrete Damage Plasticity Model (CDP) already implemented into the code allows taking into account the progressive change of stiffness of brittle supports when subjected to alternate cracking-crushing mechanisms, as well as to properly deal with the cyclic behavior. The validation of the procedure is conducted against a series of full scale masonry walls tested by Nanni and co-workers at the University of Miami. A tri-dimensional heterogeneous micro-modeling technique is also used for both unreinforced and FRCM strengthened panels to further validate the homogenization model proposed. The discretization adopted is adjusted in order to allow the presence of two eight-noded FEs along the mortar joint thickness. FRCM is modeled by means of truss elements whose mechanical properties are calibrated to reproduce the behavior of the textile net embedded into the cementitious matrix. The elastic and inelastic mechanical parameters of all the materials involved into the numerical analyses have been calibrated in agreement with laboratory tests, when available. Pros and cons of the two numerical strategies are discussed mostly with respect to the accuracy of the outcomes in terms of global behavior of the panels and damage mechanisms, as well as with respect to the computational effort required by the two approaches to complete the analyses.

Studi karakteristik gerusan lokal pada beberapa tipe pilar jembatan

The local scouringcharacteristicsuroundings several bridge pillars forms have a different characteristics, some forms of pillars of the bridge are considered optimum when equipped with the data: discharge, slope of riverbed, material, and on the same flow direction, that will produce the most shallow scouring. The objective of this study is to find the form of pillars that will generate the most superficial scouring. The study is conducted at the Laboratory of River in Surakarta. The used flume has length of 10.00 m, width 0.40 m and height of 0.40 m. The forms of pillar studied are two cylindrical pillars, sheet pile and full walls pillar. The slope of the riverbed (i) are varied, there are three: 0.006, 0.0125 and 0.020. The flow discharge rate there are five variations: 5,37 m3/s, 8,94 m3/s, 12,52 m3/s, 14,31 m3/s, 17,89 m3/s. Land was used at material for river bed, and, there are three kinds of value D50: 0.60 mm, 0.80 mm and 1.00 mm. The research method includes: a field survey, two dimension physical model test with 1:20 scale.The results showed for each pillar shapes have different characters. The deepest scouring suroundings the pillar beside the point, at the beginning of the first minute to the 20th minute in a sudden deep scour the riverbed and form of river bed suroundings are the pillars up and down irregularly. In the 20th minute until the end of the stream scouring decreased almost linearly lines are horizontzl. In general the pile type pillars was found to cause the minimum scouring than other pillar shapes.

Performance-based evaluation of strap-braced cold-formed steel frames using incremental dynamic analysis

This study is an effort to clearly recognize the seismic damages occurred in strap-braced cold formed steel frames. In order to serve this purpose, a detailed investigation was conducted on 9 full scale strap-braced CFS walls and the required data were derived from the results of the experiments. As a consequence, quantitative and qualitative damage indices have been proposed in three seismic performance levels. Moreover, in order to assess seismic performance of the strap- braced CFS frames, a total of 8 models categorized into three types are utilized. Based on the experimental results, structural characteristics are calculated and all frames have been modeled as single degree of freedom systems. Incremental dynamic analysis using OPENSEES software is utilized to calculate seismic demand of the strap-braced CFS walls. Finally, fragility curves are calculated based on three damage limit states proposed by this paper. The results showed that the use of cladding and other elements, which contribute positively to the lateral stiffness and strength, increase the efficiency of strap-braced CFS walls in seismic events.

Lightweight Woodframe Shear Walls with Ply-Bamboo Sheathings

A new type of hybrid wood-bamboo shear wall was studied. Ply-bamboo is used as the sheathing panel for conventional two-by-four lightweight woodframe shear walls herein. Two different nails were adopted for the ease constructability and used for constructing the shear walls, as follows: gun-driven T shape nail and 6d common nail. Monotonic and cyclic test results of sheathing-frame connectors and corresponding full scare shear walls were also reported. The results obtained from the research reported in this paper indicated that ply-bamboo panels can be used as sheathings for light-weight timber shear walls.

Neural representation of scene boundaries

Three-dimensional environmental boundaries fundamentally define the limits of a given space. A body of research employing a variety of methods points to their importance as cues in navigation. However, little is known about the nature of the representation of scene boundaries by high-level scene cortices in the human brain (namely, the parahippocampal place area (PPA) and retrosplenial complex (RSC)). Here we use univariate and multivoxel pattern analysis to study classification performance for artificial scene images that vary in degree of vertical boundary structure (a flat 2D boundary, a very slight addition of 3D boundary, or full walls). Our findings present evidence that there are distinct neural components for representing two different aspects of boundaries: 1) acute sensitivity to the presence of grounded 3D vertical structure, represented by the PPA, and 2) whether a boundary introduces a significant impediment to the viewer’s potential navigation within a space, represented by RSC.

Experimental study of masonry infill reinforced concrete frames with and without corner openings

Reinforced concrete frame buildings with masonry infill walls are one of the most popular structural systems in the world. In most cases, the effects of masonry infill walls are not considered in structural models. The results of earthquakes show that infill walls have a significant effect on the seismic response of buildings. In some cases, the buildings collapsed as a result of the formation of a soft story. This study developed a simple method, called corner opening, by replacing the corner of infill walls with a very flexible material to enhance the structural behavior of walls. To evaluate the proposed method a series of experiments were conducted on masonry infill wall and reinforced concrete frames with and without corner openings. Two 1:4 scale masonry infill walls with and without corner openings were tested under diagonal tension or shear strength and two RC frames with full infill walls and with corner opening infill walls were tested under monotonic horizontal loading up to a drift level of 2.5%. The experimental results revealed that the proposed method reduced the strength of infill wall specimens but considerably enhanced the ductility of infill wall specimens in the diagonal tension test. Moreover, the corner opening in infill walls prevented the slid shear failure of the infill wall in RC frames with infill walls.

Experimental investigations of sandwich panels using high performance concrete thin plates exposed to fire

Structural sandwich panels using thin high performance concrete (HPC) plates offer a possibility to address the modern environmental challenges faced by the construction industry. Fire resistance is a major necessity in structures using HPC. This paper presents experimental studies at elevated temperatures for panels with 30 mm thick plates stiffened by structural ribs, thick insulation layers, and steel shear connecting systems. Parametric variation assessing the role of each component of the sandwich structure was performed on unloaded specimens of reduced size. Full size walls were tested with load. Tests were performed in standard furnaces, following the conditions of REI certification tests. Unloaded specimens successfully passed tests. Loaded specimens met the R and I requirements, failing E due to sustained flaming of the insulation. They exhibited multiple cracking of their exposed plate and one of them experienced heavy heat-induced spalling. Results highlighted insulation shear failure from differential thermal expansion at the interface with concrete. It suggests the existence of a high bond level between the two materials which might allow structural applications at early age. Cracks resulted from buckling and thermal bowing, present in the upper and lower parts of the panel. Shear connectors created stress concentrations leading to local failure. Only ribs were found to have a structural role, the plate being largely negligible and solely protecting the insulation from heat. Performance could be enhanced by using thicker plates (50 mm).

Seismic performance of cold formed steel walls sheathed by fibre-cement board panels

This paper presents an experimental study of cold formed steel frames sheathed by fibre-cement boards (FCB) under cyclic lateral loading. Four full scale fibre-cement shear walls were tested. Of particular interests are the specimens maximum lateral load capacity and the load–deformation behaviour as well as a rational estimation of the seismic response modification factor, R factor. The study also looks at the failure modes of the systems and investigates the main factors contributing to the ductile response of the CFS shear walls in order to suggest improvements so that the FCB sheathed walls respond plastically with a significant drift and without any risk of brittle failure such as connection failure or fibre-cement board fracture. Both double-sided and single-sided FCB shear panels as well as a new proposed configuration were studied. The study shows that while the overall performance of the currently in-use FCB sheathed lateral resistant system under cyclic loads is not satisfactory with a small average R factor of 2.5, the proposed FCB lateral resistant system can be considered as a reliable system with a much higher value of R factor of 5.

Experimental Characterization of the In-plane and Out-of-Plane Behaviour of Infill Masonry Walls

The infill masonry (IM) walls are considered non-structural elements but, when subjected to earthquakes, they tend to interact with the surrounding RC frames, which can result in different failure modes depending on the combinationof the in-plane and the out-of-plane behaviour. Therefore,the contribution of infill masonry panels should be considered in the structural response analysis of existing buildings, for which understanding the out-of-plane non-linear behaviour of IM walls is paramount to develop efficient strengthening solutions to prevent and improve their performance in future earthquakes and, consequently,to reduce their seismic vulnerability. In order to obtain further knowledge concerning the out-of-plane response of IM panels, anexperimental testing campaign of full scale IM walls was started at the Laboratory of Earthquake and Structural Engineering – LESE by performing three experimental (cyclic and monotonic) out-of-plane tests with and without previous in-plane damage. The general specimen dimensions are representative of thoseexisting in a large portion of the Portuguese building stock according to recent studies. The experimental campaign and test setup will be described and the experimental tests’ results will be presented and discussed in the paper, namely in terms of hysteretic force-displacement curves and damage evolution.

Earthquake Response of RC Infilled Frame with Wall Openings in Low-rise Hotel Buildings

To study the earthquake response of RC infilled frame structures with variable wall opening, 3-D computer models were made for 3, 4, and 5 storey typical hotel buildings consisting of six frames of 3 bays. In X-direction, the middle bay was open and the side bays were in-filled with full (solid) walls. In Y-direction, the interior walls consisted of door opening in the corner and the exterior walls consisted of window openings with variable ratios of 20%, 40%, 60%, 80%, and 100%. Prior to modeling the 3-D structure, 2-D validation models using diagonal strut and shell element were made based on test results of simple infilled frames with various openings. For the strut model, the wall with opening was modeled using diagonal strut of reduced width. For the shell element model the wall was modeled as is with gap element at the interface between the frames and the wall. Considering crack development and non linear stress-strain relationship of the materials, the lateral load-displacement diagrams of the shell element models fit the test result better than the strut ones. Models with lintels around the wall openings were also created for validation and the results show that lintels stiffen the frame and strengthen the wall around the openings. The shell element model was then used to create 3-D models of the hotel building with lintels around the wall openings. Analysis and design of the 3-D models show that the earthquake responses of RC frames infilled with walls of opening ratios 20% to 60% are significantly stiffer and stronger than that without infill wall. However, the contribution of infill walls with 80% opening in reducing storey drift and frame reinforcement was much smaller. Accordingly, the infill walls with opening ratios of less than 80% should be considered in the structural modeling to obtain a more accurate analysis and efficient design.

Investigation of Zeff and impurity behaviour in lithium coating experiments with full metallic first wall in HT-7 tokamak

The control of the impurity level in magnetically confined plasmas is a critical issue for future fusion devices. All the graphite tiles have been replaced by molybdenum tiles as limiter materials in the 2011 spring campaign in order to further reduce the recycling and hydrogen content of the plasma. A lithium coating technique has been applied as an important wall conditioning method to the HT-7 tokamak. The effective ion charge Zeff and impurity behavior with full metallic first walls of high-Z materials and lower hydrogen recycling have been investigated in a series of lithium coating experiments in this paper. Plasma performance and impurity behavior without wall coatings are studied in the early stage of the campaign. Comparison of Zeff with different plasma-facing components has been made. A typical lithium coating experiment has been analyzed in order to understand the effect of lithium coating. The evolution of main impurity line radiation, Zeff and the H/(H + D) ratio is analyzed in detail as lithium coating is repeated, indicating that lithium coating is a very effective tool to control impurity level and reduce hydrogen recycling. Furthermore, a boronization is conducted at the end of this campaign in order to make comparison with lithium coating. Experimental results show that lithium coating has much more advantages in edge recycling control, though it does not reduce impurity level as effectively as boronization.

Cracking in autoclaved aerated concrete: Experimental investigation and XFEM modeling

The paper aims to investigate and model cracking development in beams and deep-beams made of autoclaved aerated concrete (AAC). Fracture mechanics of AAC has been first studied by performing three-point bending tests on beams, similar to those commonly used for ordinary concrete elements. In some of these tests, crack growth has been also monitored by using ESPI laser technique. In this way, it has been possible to calibrate the main parameters of a proper cohesive law by means of extended finite element inverse analysis. Subsequently, cracking tests have been also performed on deep-beams, whose behavior is more representative of full scale walls. To validate the proposed cohesive law, deep-beam experimental behavior has been finally simulated through XFEM.

Impact of flood defences and sea-level rise on the European Shelf tidal regime

The tidal response of the European Shelf to moderate (<1m) levels of sea level rise is investigated using a high resolution, well established tidal model. The model is validated for present day conditions and the tidal response to sea level rise by comparing the modelled response to long term tide gauge data. The effects of coastal defence schemes are tested, with three levels of present day coastal defences simulated. Full walls are added at the present day coastline, no coast defence schemes are used and a set of present day coastal defence schemes is simulated. The simulations show that there is a significant tidal response to moderate levels of SLR and that the response is strongly dependant on level of coastal defence simulated. The simulation using coastal defence data resulted in the strongest response as the tide was able to build up behind the coastal defence walls and create a patchwork of sea and land at the coastline. This had a strong impact on the spatial tidal energy dissipation field and in turn this has large effects on the tidal regime throughout the domain.

G17 Transforming the design of a children’s emergency department – simulation as a powerful service development tool

AimTo utilise large scale simulation to assess the full system functioning of a children’s emergency department prior to actually constructing the building. The simulation aimed to identify the impact of...

An overview of the comprehensive First Mirror Test in JET with ITER-like wall

The First Mirror Test in Joint European Torus (JET) with the International Thermonuclear Experimental Reactor-like wall was performed with polycrystalline molybdenum mirrors. Two major types of experiments were done. Using a reciprocating probe system in the main chamber, a short-term exposure was made during a 0.3 h plasma operation in 71 discharges. The impact on reflectivity was negligible. In a long-term experiment lasting 19 h with 13 h of X-point plasma, 20 Mo mirrors were exposed, including four coated with a 1 μm-thick Rh layer. Optical performance of all mirrors exposed in the divertor was degraded by up to 80% because of beryllium, carbon and tungsten co-deposits on surfaces. Total reflectivity of most Mo mirrors facing plasma in the main chamber was only slightly affected in the spectral range 400–1600 nm, while the Rh-coated mirror lost its high original reflectivity by 30%, thus decreasing to the level typical of molybdenum surfaces. Specular reflectivity was decreased most strongly in the 250–400 nm UV range. Surface measurements with x-ray photoelectron spectroscopy and depth profiling with secondary ion mass spectrometry and heavy-ion elastic recoil detection analysis (ERDA) revealed that the very surface region on both types of mirrors had been modified by neutrals, resulting eventually in the composition change: Be, C, D at the level below 1 × 1016 cm−2 mixed with traces of Ni, Fe in the layer 10–30 nm thick. On several exposed mirrors, the original matrix material (Mo) remained as the major constituent of the modified layer. The data obtained in two major phases of the JET operation with carbon and full metal walls are compared. The implications of these results for first mirrors and their maintenance in a reactor-class device are discussed.

The development and analysis of a large variable acoustics space

A new, large-scale variable acoustics space has recently been added to the Audio Arts &amp; Acoustics department at Columbia College Chicago. Built within the current Motion Capture studio, this facility will provide students and faculty the ability to perform tests in an acoustically controlled environment, without the influence of small-room effects. The construction involved the creation of nearly 300 2 in. x 2 in. reversible boxes: one side diffusive and the other absorptive. These line three full walls of the space at a height of 10 in., totaling ~1200 ft2 of acoustically adjustable surface area. This allows the room to convert from a very absorptive space, to one that is much more acoustically active. Multiple specular reflector panels are also available for the creation of “hot spots,” allowing for even more diverse applications. This study focused on the construction and initial testing of this innovative new space. To analyze the effectiveness of the additions, frequency, time, and reverberation responses for the entire room were sampled in a variety of configurations: fully absorptive, fully diffusive, empty, etc. These objective metrics were then analyzed against perceptual data to determine the correlation between what could be measured and what could be heard.